Continuous delivery of medicinal fluid to a patient has been proven beneficial in instances of severe pain, infection, and other medical ailments. Medicinal fluid is often parenterally infused to treat humans and/or animals. The medicinal liquid is infused in a predetermined flow pattern (continuous, intermittent, or variable), and, in some cases, the infusion therapy can last a long time. For example, there are cases which require infusion of drugs, antibiotics, lipids, blood, blood products, enteral solutions, or other therapeutic solutions.
One common apparatus for infusing fluid into a patient is a syringe pump. A syringe pump is a device on which a syringe (usually disposable) with fluid is loaded and the pump drives the syringe plunger to deliver the fluid inside the syringe. The syringe barrel is secured on the pump and the syringe plunger disc is pushed by the pump's plunger driver. The plunger driver is driven by a leadscrew mechanism that is attached to a gearbox/motor assembly located inside the pump. A clutch lever is used to operate a clutch mechanism to engage or disengage the plunger driver from the leadscrew. Thus, the plunger driver can be positioned at the end of the syringe plunger disc to be ready for driving the syringe plunger. The syringe plunger disc has to be secured by the plunger driver to prevent the possibility of over-infusion due to uncontrolled siphoning.
Almost all syringe pumps have a guard gate integrated with the plunger driver to protect the plunger from siphoning. Normally, the loading of the syringe plunger disc is performed after the syringe barrel is firmly loaded onto the syringe pump. If the guard gate is a fixed structure, the user must use one hand to lift the syringe plunger disc over the guard gate and the other hand to actuate the clutch lever to position the plunger driver. Generally, the plunger disc is protected only on the lower side, this fixed type is not only inconvenient but also does not work well for different syringe sizes. The plunger disc can inadvertently become disengaged during use, which can result in over-delivery of the medical fluid and cause harm to a patient. The newer syringe pumps have moving or swinging gates that can be moved or swung out when the clutch lever is actuated to position the plunger driver. The gates will move or swing back to be in front of the plunger disc when the clutch lever is released. Since the thickness of the plunger disc varies for difference syringe sizes, there will be a gap between the gates and the plunger disc if the moving gates cannot move toward the plunger disc to apply force onto the plunger disc to firmly hold the plunger disc onto the plunger driver. Fluctuation of the pressure in the infusion line can affect the plunger disc position and the infusion accuracy if there is a gap between the guard gate and the plunger disc. Due to this gap, the plunger disc is more likely to become disengaged from the guard gate and can cause harm to the patient.
Therefore, there is a need for a syringe pump that provides an easy syringe loading operation and secures firmly the syringe plunger disc during the operation, and it is to this apparatus the present invention is primarily directed to.